As zygote moves along oviduct > produces morula
- As zygote divides, cells become smaller
- Movement by cilia and peristalsis present in oviduct walls
Morula develops into a blastocyst
- Trophoblast (outer layer of blastocyst) nourishes future embryo
- Inner cell mass will become foetus
- Fluid filled cavity for protection (absorbs shocks, resists compression, ...)
Blastocyst (?100cells) implants itself in uterus lining
- Nourished by secretion from uterus
- Microvilli provide large surface area (? gas + nutrients exchange)
Week 2
Trophoblast secretes enzymes ? digest tissues and blood vessel of endometrium
Embryo uses released nutrients/products from digestion
Blastocyst becomes buried within endometrium
Microvilli are replaced by placenta
Trophoblast secretes human chorionic gonadotrophin (hCG) hormone
